In my vswitch patches I've renamed networkStartNetworkDaemon to
networkStartNetworkVirtual, and added separate functions for host
bridge-based networks and macvtap networks, so 1) there will be a slight
merge conflict, and 2) you will want to add a call to virBandwidthEnable
at least to the host bridge version (I'm not sure how you can implement
a network-wide bandwidth limit for the macvtap-based networks, since
they can have multiple interfaces.

Also, what happens when libvirt is restarted? Do we need to "reload" the
tc configuration as we do with iptables rules (in case some other
application has messed with them)?